Cartridge fuse



March 16, 1937. o. H. JUNG ET AL CARTRIDGE FUSE Filed Oct. 29, 1954 Patented Mar. 16, 1937 CARTRIDGE FUSE Oscar H. Jung and Paul E. Heifelfinger, Milwaukee, Wis., assignors to Trico Fuse Manufacturing Co., Milwaukee, Wis., a corporation of Wisconsin Application October 29, 1934, Serial No. 750,499

4 Claims. (Cl. ZBO- 131) This invention relates to electric fuses, and more particularly to that type commonly known as a renewable knife blade cartridge type.

Fuses of the foregoing character are so con- 5 structed that the terminals are readily removable from the casing, to permit renewal of the fuse link and facilitate cleaning of the casing after the fuse is blown. To accomplish this, it is customary to lock one of the terminals against longitudinal movement, with the result that upon blowing of the fuse the opposite terminal is free to move into the casing and cause possible arcing and undesired closing of the circuit. Also, when only one of the terminals is anchored, considerable strain is placed upon the soft renewal link, frequently causing the same to warp and sag.

`To overcome the foregoing objections, numerous attempts have been made to lock both terminals against longitudinal movement, as well as against rotation, but these have been costly, complicated, and awkward. It is therefore the primary object of the present invention to provide an exceedingly simple and inexpensive fuse, which can be quickly and easily renewed, and in which the terminal inserted through the casing is securely locked against longitudinal movement.

Incidental to the foregoing, a more specic object of the present invention is to provide resilient means for clamping engagement with one of the fuse link terminals, said means being operatively eifected upon actuation of a cap connected with the end of the casing.

A still further object resides in the provision of a split resilient ring adapted to be forced into binding engagement with the edge or edges of one of the terminal knife blades upon actuation of a cap associated with the terminal receiving member.

With the above and other objects in View, which will appear as the description proceeds, the invention resides in the novel construction, combination, and arrangement of parts, substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the herein disclosed invention may be made as come within the scope of the claims.

In the accompanying drawing is illustrated one complete example of the physical embodiment of the present invention constructed according to the best mode so far devised for the practical application of the principles thereof.

In the drawing:-

Figure l is an elevation of a renewable knife blade cartridge fuse, partly broken away and in section to more clearly illustrate structural details.

Figure 2 is an end elevation, partly in section.

Figures 3 and 4 are fragmentary elevations of 5 a modified form of the invention, parts being broken away and in section.

For illustrative purposes only, a more or less conventional structure of fuse has been shown. However, it is to be understood that the inven- 10 tion, which resides primarily in the provision of novel means for locking the knife blade terminal against longitudinal movement, may be applied to various structures of cartridge fuses, without departing from the principles thereof, and there- 15 fore the invention is not to be limited in any way to the structure of the terminal, or terminal receiving member.

In that type of fuse disclosed, the numeral I designates a cylindrical casing, usually formed 20 of libre, and having its end internally threaded at 2, for the reception of a shouldered sleeve 3, the exposed shoulder portion being externally threaded to receive an end cap 4. Seated upon the end of the sleeve 3, and held against rotation thereo-n in any suitable manner, is a slotted disc 5, which receives the knife blade terminal 6 to hold the same in alinement with the opposite terminal. The usual fusible link 1 is detachably connected to the inner end of the terminal blade 30 6 by a bolt 8, or other conventional form of attachment, and rigidly mounted on the shank of the blade 6 is a washer 9, which abuts the inner face of the slotted disc 5 to limit projection of the blade through the disc, and also to effectively 35 close or obstruct the opening between the slot in the disc 5 and the blade.

In conventional fuse structures the slotted disc is locked upon the sleeve 3 by the threaded cap 4, the inturned annular ange 4 being of suf- 40 cient diameter to clear the blade and engage the outer face of the dise 5 adjacent its periphery.

On the other hand, a closure for the end of the fuse can be effected by forming the slotted end integral with the sleeve 3. However, this is not 40 as desirable as the structure illustrated, in that the sleeves 3 are usually permanently connected to the ends of the casing by rivets, or other forms of permanent attachment, and, therefore, difliculty is encountered in effectually cleaning the ""U interior of the casing after the fuse is blown.

As best shown in Figure 1, the inner periphery of the flange 4 is conically formed to provide an annular tapered face I0, which engages a resilient split ring Il positioned against the outer face of the slotted disc 5. Due to the resiliency of the ring I I, the same is normally expanded to permit the blade 6 to be projected through the slotted disc 5 and the end cap 4. However, as the cap 4 is turned down upon the shouldered threaded portion of the sleeve 3, the tapered face, engaging the ring II, causes the same to be retracted and forced into binding engagement-with'the edges of the blade 6, thus effectively locking the blade against longitudinal movement. While it is not essential to lock the split ring II against rotation, should this be desired one end of the ring may be turned downwardly at Il for engagement in a recess 5 formed in the disc 5 adjacent its outer periphery. Obviously, rotation of the cap 4 will then have no turning effect upon the ring I I, eliminating a possibility of the split ends of the ring straddling one `edge of the bladeV 6, which may otherwise occur. l

Referring now more particularly to that form of the invention disclosed in FigureslB andv 4, the Ylocking operation `is reversed, in thatr the split resilient ring II is seated upon a tapered annular face `I2 formed internally at the end of the sleeve 3. In this instance, the blade 6 has rigidly secured thereto a'conical washer I3, v1nstead of the flat washer 9 heretofore described, and in operation, as the-cap I4 is turned down on the sleeve 3", theslotted disc `5, vengaging the ring 'I I, forces the same downwardly on the taperedlface I2, causing the ring to be retracted andV forced into binding engagement with the conical washer I3. l

As best shown in Figure 3, the ring II 1s normally expanded so as to permitrthe blade 6 to pass through the same during'assembly of the fuse. Then, as the capr I4 is turned down to lock the slotted disc 5 on the end of the sleeve 3', the ring is retracted, as shown in Figure 4. The advantage of this structure resides in the fact that the conical washer serves to center the terminal with relation to the casing, and inasmuch as the split ring II is forced into binding engagement with the washer throughout substantially its entire periphery the terminal is securely and firmly held against lateral tilting in any direction.

From the foregoing explanation, considered in connection with the accompanying drawing, it will be readily seen that an exceedingly simple, inexpensive, and effective method has been devised for locking the terminal of a knife blade renewable fuse against longitudinal movement, and inasmuch as the point of engagement between the terminal andthe resilient clamping member may vary, shrinkage or expansion of the casing I will have no effect upon the locking of the terminal.

Also, particular attention is directedv to the factthat it is in no way necessary to alterthe structure of conventional fuses, in order to apply the present invention, other than to provide a, tapered, annular face upon one of the terminal receiving members for camming and forcing the split ring into binding engagement with the terminal. In renewing the link or cleaning the casing, slight turning of the caps 4 or I4 quickly relieves the bind on the terminals, and permits the same to be readily withdrawn and again inserted. For the purpose of economy, the split ring I I is preferably formed from round spring wire. However, it is to be understood that various types and structures f resilient clamping members may be employed, and also while it is preferred to grip the opposite edges of the knife blade, the clamping member may be so designed as to engage only one edge of the blade.

f In equipping the fuse with the present invention, no additional mechanical operations are required, it being merely necessary to snap or insert the split ring into position between the retaining elements.

We claim:-

1. A renewable knife blade cartridge fuse comprising a casing, a wrenewable fuseelement in cluding knife blade terminals, 4terminal receiving members carried by the ends of` Vthefcasing,

`resilient means associated with one of said terminal receiving members for binding engagement with at least one edge of the terminal received thereby, and means carried by said memberfffor forcing said resilient means into engagement with the terminal.

2. A renewable knife blade cartridge fuse comprising a casing, a renewable fuse element including knife blade terminals, terminal receiving members carried by the ends of the casing, a resilient split ring associated with one of said terminal receiving members for bindingengagey" ment with the edges of the terminal received thereby, and means' carried by said memberffor forcing said ring into engagement with the'terminal. y

3. A renewable knife blade cartridge fuse coniprising a casing, a renewable fuse element in-v cluding knife blade terminals, terminal receiving members carried by the ends of the casing, a resilient split positioned against the outer face of one of said terminal receiving members, and

a rotatable cap connected with said terminal receiving member for camming the split ring into binding engagement with the edges of the terminal.

4. A renewable knife blade cartridge fuseV comi prising a casing, a renewable fuse element including knife bladeterminals, terminal-receiving Vmembers carried by the en ds of the casing-,fa

resilient split ring associated with one of said terminal-receiving members for binding engagement with at least one edge of the terminal received thereby, said ring having interengagement with the terminal-receiving member to prevent relative movement, andmeans carried by said terminal-receiving member for forcing said ring into engagement with the edge of the terminal.

OSCAR H. JUNG. PAUL E. I-IEFFELFINGER.` 

